AMS测量中同量异位素的鉴别方法

在加速器质谱测量中,存在同位素和同量异位素的干扰.排除同位素的干扰是开展超微量核素分析的重要课题之一.主要介绍了加速器质谱测量中同量异位素的几种鉴别、排除方法,以及这些方法的原理、发展及应用. There are interference of isotopes and isobars in accelerator mass spectrometry (AMS) measurements. Eliminating the isobaric interference is the important aspect in AMS measurements. Several methods of isobaric identification in AMS measurements are discussed in this paper. Principles, developments and applications of these methods are also introduced.     

Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

Based on the first ionization chamber (IC) prototype, the structure, working gas component and electrode material of the IC are improved. The test of the improved IC shows that the plateau length is about 2000 V, the plateau slope is less than 0.2%/100 V, the sensitivity is 19.6 pA/rad·h^-1, the up-limitation of the linearity can be up to 3.6×10⁵ rad/h, and the applied voltage can be operated to 3500 V. The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.     

A Bragg curve detector and its application in AMS measurements for medium-weight nuclides

The schematic layout and principle of a Bragg curve detector were showed in this paper. A Bragg curve detector was systemically modified and its performance was improved. The total energy resolution of the detector is 0.9% for alpha particle at energy of 5.48 MeV from ²⁴¹Am source, and the Bragg Peak resolution is 1.6%. Measurement of medium-weight nuclides by using the Bragg curve detector were carried at CIAE-AMS system. series of ³⁶Cl and ⁴¹Ca standard samples were measured. The results showed that this Bragg curve detector could clearly identify isobars ³⁶Cl-³⁶S and ⁴¹Ca-⁴¹K. The results also showed that the ΔZ/Z of 1/47, corresponding to Bragg Peak resolution is 2.1% at ion atomic number of about 16. The Bragg curve detector can be successfully used for AMS measurement.     

灰岩侵蚀速率的研究

测定不同地貌环境下的侵蚀速率是了解地表形成及演化的基础。目前,已有人用10Be/26Al双核素和宇宙成因核素36Cl来研究灰岩表面的侵蚀速率和暴露年龄。本工作通过36Cl的AMS测量计算了北京地区灰岩表面的侵蚀速率,其结果为(1.33±0.28)×10-5m.a-1。     

位置灵敏型~3He正比管对γ的误判率

位置灵敏型3He正比管主要用于热中子的探测。考虑到有些探测环境中有γ存在,所以本文主要研究3He正比管对γ的误判率,通过实验和Geant4蒙特卡罗模拟的结果,讨论在一定γ本底情况下,3He管探测器是否适合进行热中子探测。     

~(36)Cl的加速器质谱测量及其应用

长寿命核素36Cl的半衰期为3.01×105a,广泛分布于自然界中。加速器质谱是目前测量36Cl的最灵敏的方法。介绍了36Cl的样品制备及加速器质谱测量方法,重点描述了基于小型化加速器质谱发展起来的测量36Cl的探测方法及其特点,综述了各实验室利用36Cl在相关领域开展的工作及所取得的成果。     

西门子S7-200 PLC在SISAK快化分离装置中的应用

SISAK是国内外目前应用最广泛的短寿命同位素快化分离技术之一,在裂变产物、超重元素、远离β稳定线的非稳核研究方面有着广泛的应用。SISAK技术最新的发展主要集中在配套设备和计算机控制上。我们研制了一套以S7-200 PLC为核心的SISAK自动控制系统,其组成和控制方案简单可靠,已在冷实验中取得了很好的效果。     

Developing AMS measurement of 59Ni at CIAE

Accelerator mass spectrometry (AMS) measurement of ⁵⁹Ni has been established at CIAE with the HI-13 tandem accelerator and the recently developed ΔE-Q3D detection system. ⁵⁹Ni standard and commercial NiO samples were measured to check the performance of the ΔE-Q3D detection system on ⁵⁹Ni isobar separation and suppression. An overall suppression factor of about 10⁷ for the interfering isobar ⁵⁹Co resulting in detection sensitivity as low as 3.8×10^-13 atomic ratio (⁵⁹Ni/Ni) has been obtained. Based on these techniques, the AMS measurement method of ⁵⁹Ni with high sensitivity is developed.     

误差与不确定度几个问题的讨论

测量误差与测量不确定度紧密联系,但却有区别。本文从定义、分类等角度讨论了二者的关系,并对不确定度的计算提出了作者的一些见解。